We will continue to develop the laboratory rabbit as a research tool by the characterization of the immunobiological properties of inbreeding and non-inbred selectively bred animals. We will stress studies of the cellular antigens controlled by blood group loci and loci associated with the major histocompatibility complex. On the basis of our knowledge of the cellular antigens we will study the rabbit as a model for organ transplantation, for cancer early detection and immunotherapy and as a model for certain problems of oral biology. We will study the significance of polymorphic genes during inbreeding and continue our studies on the genes comprising the major histocompatibility complex. We will continue to supply immunogenetically defined rabbits, erythrocyte and tissue typing sera and typing service to all qualified investigators.